Epithelial NMIIA deficiency impairs ring cell function. (A and B) Optical sections (planar and sagittal views) of confocal images from Myh9 cKO and control littermate embryos labeled with EpCAM (white; A), F-actin (phalloidin, represented in LUT depicted in the middle panel), and pMLC (represented in LUT depicted in the right panel) (B) at hillock (E12.5), bud (E13.0), and bulb (E13.5) stages. Scale bar, 50 µm. Arrowheads mark the increased intensity. Arrows mark ring cells still present at E13.0. (C and D) Quantification of F-actin (C) and pMLC (D) intensity in ring cells (0–30 µm from the bud) and epidermal cells (EC; 70–100 µm away from the bud) of four to seven control and four to six Myh9 cKO embryos per stage (Controls: n_{E12.5 Ring cells} = 621, n_{E12.5 EC} = 252, n_{E13.5 Ring cells} = 648, n_{E13.5 EC}= 787; Myh9 cKO: n_{E12.5 Ring cells} = 568, n_{E12.5 EC} = 108, n_{E13.5 Ring cells} = 495, n_{E13.5 EC} = 652). Data shown represent median (line) with 25th and 75th percentiles (hinges) plus 1.5× interquartile ranges (whiskers). Statistical significance within each stage was assessed with the Mann-Whitney U test with Bonferroni correction. AU, arbitrary units. *, P ≤ 0.05; **, P ≤ 0.01; ****, P ≤ 0.0001.